Gear Ratios

smithy05

I am looking at buying a Giant TCR advanced 1 which has a 53/39 Chainset on it. My LBS won't swap it out for a compact free of charge, instead will charge me £150 for the new compact, leaving me to sell the Standard double. The bike comes with an 11-25 cassette, if I were to change the cassette to a 11-28, leaving the standard double on, would I get similar ratios to the compact with original cassette?

Grill

Yes as both bottom ratios are 1.4.

smithy05

What would the spread of the gears be like? Fairly similar?

bernithebiker

smithy05 wrote:

What would the spread of the gears be like? Fairly similar?

Here's the 11-28 cassette;

11, 12, 13, 14, 15, 17, 19, 22, 25, 28

Here's the 11-25;

11, 12, 13, 14, 15, 17, 19, 21, 23, 25

So apart from the lowest 3 gears, they're the same. You'll just get bigger jumps (3 tooth i/o 2 tooth) when you change up in the lowest gears.

A lot depends on your level/fitness and where you're riding the bike. If it involves hills and you're not well up there fitness wise, I would always say go with the compact.

mamba80

I would say first try an ring around and see if another BS will do the swop for free or cost.

Otherwise instead of Shimano cassette, get a 12/28 from Sram pg1070, the Shimano's lowest gears are 21 - 24 - 28 - even bigger jumps than above example - i doubt you ll ever need a 53 /11.

schweiz

11	  12	  13	  14	  15	  17	  19	  21	  23	  25
50   4.55	4.17	3.85	3.57	3.33	2.94	2.63	2.38	2.17	2.00
34   3.09	2.83	2.62	2.43	2.27	2.00	1.79	1.62	1.48	1.36
								
      11	  12	  13	  14	  15	  17	  19	  22	  25     28
53   4.82	4.42	4.08	3.79	3.53	3.12	2.79	2.41	2.12	1.89
39   3.55	3.25	3.00	2.79	2.60	2.29	2.05	1.77	1.56	1.39